ladybird/AK/Weakable.h
2023-11-09 16:02:14 +01:00

95 lines
1.6 KiB
C++

/*
* Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Assertions.h>
#include <AK/RefCounted.h>
#include <AK/RefPtr.h>
#include <AK/StdLibExtras.h>
namespace AK {
template<typename T>
class Weakable;
template<typename T>
class WeakPtr;
class WeakLink : public RefCounted<WeakLink> {
template<typename T>
friend class Weakable;
template<typename T>
friend class WeakPtr;
public:
template<typename T>
RefPtr<T> strong_ref() const
requires(IsBaseOf<RefCountedBase, T>)
{
return static_cast<T*>(m_ptr);
}
template<typename T>
T* unsafe_ptr() const
{
return static_cast<T*>(m_ptr);
}
bool is_null() const { return m_ptr == nullptr; }
void revoke() { m_ptr = nullptr; }
static FlatPtr ptr_offset() { return OFFSET_OF(WeakLink, m_ptr); }
private:
template<typename T>
explicit WeakLink(T& weakable)
: m_ptr(&weakable)
{
}
mutable void* m_ptr { nullptr };
};
template<typename T>
class Weakable {
private:
class Link;
public:
template<typename U = T>
WeakPtr<U> make_weak_ptr() const
{
return MUST(try_make_weak_ptr<U>());
}
template<typename U = T>
ErrorOr<WeakPtr<U>> try_make_weak_ptr() const;
protected:
Weakable() = default;
~Weakable()
{
revoke_weak_ptrs();
}
void revoke_weak_ptrs()
{
if (auto link = move(m_link))
link->revoke();
}
private:
mutable RefPtr<WeakLink> m_link;
};
}
#if USING_AK_GLOBALLY
using AK::Weakable;
#endif